Medical Fundamentals Comprehensive Review — The Science of Maintaining Health and Preventing Disease

Medical Fundamentals Series — Complete Summary

Chapter	Organ System	Core Concepts
Ch1	History of Medicine	Evidence-based medicine (EBM)
Ch2	Cells and Tissues	Cell structure, organ system hierarchy
Ch3	Cardiovascular	Cardiac cycle, hypertension
Ch4	Respiratory	Gas exchange, pulmonary diseases
Ch5	Nervous System	Neurons, stroke
Ch6	Endocrine System	Hormones, diabetes
Ch7	Immunology	Innate and adaptive immunity, vaccines
Ch8	Digestive System	Nutrient absorption, IBD
Ch9	Musculoskeletal & Skin	Fractures, osteoporosis, atopic dermatitis
Ch10	Comprehensive Review	Preventive medicine, health management

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Integrated Understanding of the Organ Systems

The human body does not operate as a collection of independent organs — every system is closely interconnected.

Cardiovascular–Respiratory link:
Lungs oxygenate blood → heart pumps it throughout the body
→ Heart failure → fluid accumulates in the lungs → shortness of breath

Endocrine–Immune link:
Stress → cortisol rises → immune suppression
Diabetes → reduced immune function → increased susceptibility to infection

Nervous–Endocrine link:
Hypothalamus → pituitary gland → peripheral endocrine glands
HPA axis: central hub of the stress response

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The Three Levels of Preventive Medicine

Primary prevention (before disease develops):
→ Vaccination
→ Lifestyle modification (exercise, diet, smoking cessation)
→ Elimination of environmental risk factors

Secondary prevention (early detection):
→ Health screenings (early cancer detection)
→ Screening tests (blood pressure, blood glucose, cholesterol)
→ Intensive management of high-risk populations

Tertiary prevention (preventing complications):
→ Diabetic patients → regular retinal and kidney exams
→ Post-myocardial infarction → medication and rehabilitation for relapse prevention
→ Maintaining quality of life

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Korea’s National Health Screening Guide

General health checkup (every 2 years):
→ Blood pressure, blood glucose, total cholesterol, triglycerides
→ Height, weight, waist circumference (abdominal obesity)
→ AST/ALT (liver function), creatinine (kidney function)

Cancer screening:
Stomach cancer: endoscopy every 2 years from age 40
Colorectal cancer: fecal occult blood test every 1–2 years from age 50
Liver cancer: ultrasound + AFP every 6 months from age 40 (high-risk group)
Breast cancer: mammography every 2 years for women from age 40
Cervical cancer: Pap smear every 2 years for women from age 20
Lung cancer: low-dose CT every 2 years for smokers aged 54–74

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Lifestyle Medicine — The Most Powerful Medicine

Evidence-based lifestyle prescriptions:

Physical activity:
→ At least 150 minutes of moderate aerobic activity per week
→ Strength training at least twice a week
→ Benefits: 30% reduction in cardiovascular disease risk, 27% in diabetes, 21% in cancer

Diet:
→ Mediterranean diet: olive oil, vegetables, fish, whole grains
→ Minimize ultra-processed foods
→ Limit sodium (below 2,000 mg/day)

Sleep:
→ 7–9 hours (adults)
→ Chronic sleep deprivation → obesity, diabetes, cardiovascular disease, immune decline

Stress management:
→ Chronic stress = root of many diseases (inflammation, immune suppression)
→ Mindfulness, exercise, and social connection are effective strategies

Smoking and alcohol:
→ Smoking: 15–25× increased lung cancer risk, 2–4× cardiovascular risk
→ Alcohol: more than 1 standard drink/day = increased risk of multiple cancers

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Chronic Disease Prevention Checklist

Cardiovascular disease prevention:
☐ Maintain blood pressure below 120/80 mmHg
☐ LDL cholesterol below 100 mg/dL
☐ Quit smoking (cardiovascular risk halved within 1 year)
☐ Regular aerobic exercise

Diabetes prevention (prediabetes):
☐ 5–7% body weight reduction
☐ 150 minutes of physical activity per week
☐ Reduce refined carbohydrate intake
→ 58% reduction in diabetes onset risk (DPP study)

Cancer prevention:
☐ Quit smoking (lung, oral, bladder, pancreatic cancer)
☐ Maintain healthy weight (obesity linked to 13 cancers)
☐ Complete all recommended national cancer screenings
☐ Hepatitis B vaccination (liver cancer prevention)
☐ HPV vaccination (cervical cancer prevention)

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How to Approach Medical Knowledge

Medical information literacy:
→ Check the level of evidence: systematic reviews > randomized controlled trials > cohort studies > case reports
→ Correlation ≠ causation
→ Statistical significance ≠ clinical significance

Beware of "N=1":
→ "I ate this and got better" = a single case report
→ Not the same as results from studies of thousands of people

Partnership with your doctor:
→ Record symptoms accurately (when they started, under what circumstances, associated symptoms)
→ Disclose all medications and supplements you're taking
→ Don't hesitate to ask questions

Medicine is the science of uncertainty and the art of possibility. — William Osler